Static and cyclic fatigue behaviour of crack-healed Si3N4/SiC composite ceramics

Effect of frequency on high-temperature fatigue crack growth in a silicon carbide reinforced silicon nitride composite

“…the crack open, to prevent healing during heating to the test temperature, any applied load that was above the threshold stress intensity caused crack growth, often leading to unpredictable failure. Similar crack healing effects have been reported by a number of researchers [18,19]. The continuous crack growth during static loading at 1000°C can be considered with reference to fracture toughness.…”

Generic principles of crack-healing ceramics

“…Early work focused on crack healing of surface cracks of polycrystalline UO 2 [21,22], Al 2 O 3 [23] and MgO [24]. Since then, a large number of ceramic materials were demonstrated to exhibit crack healing capability including silicon carbide [25,26], silicon nitride [27,28], single crystalline sapphire [29], alumina [15,30,31], mullite [32,33], zirconia [34], or MAS glass ceramics [35]. The temperatures to initiate healing reaction, however, were found to exceed 0.7-0.9 of the melting temperature of single crystals or equal the sintering temperature of polycrystalline ceramics.…”

Crack-healing behavior and resultant strength properties of silicon carbide ceramic

“…Therefore, for this crackhealed specimen of SiC ceramic it was assumed that the limiting temperature for bending strength is relatively low, because the crack-healing material of this SiC is glassy SiO 2 , as mentioned in Section 3.1. The previous studies 24,26 Fig. 8.…”

“…Therefore, the maximum crack size that can be healed completely is 2c max ≈ 50 m in surface length. The previous studies [23][24][25][26] showed that sufficient temperature and time is necessary for crack healing. However, the bending strength of specimens crack healed at 1573 K could not recovered despite increasing the holding time, as shown in Fig.…”